Thermoplastic container with side wall and rim strengthening characteristics



g- 1956 T. N. GAUNT 3,268,144

THERMOPLASTIC CONTAINER WITH SIDE WALL AND RIM STRENGTHENINGCHARACTERISTICS Filed March 23, 1964 INVE NTOR: Thomas Norman GauntUnited States Patent 3,268,144 THERMOPLASTIC CONTAINER WITH SIDE WALLAND RIM STRENGTHENING CHARACTERISTICS Thomas Norman Gaunt, Leeds,England, assignor to Illinois Tool Works Inc., Chicago, Ill. Filed Mar.23, 1964, Ser. No. 354,170 Claims priority, application Great Britain,Mar. 25, 1963, 11,641/63; Nov. 16, 1963, 45,342/63 1 Claim. (Cl.229--2.5)

The present invention relates to trays or containers formed fromthermoplastic material having strengthening and rigidifyingcharacteristics.

One of the inherent difficulties of trays or containers formed fromthermoplastic sheet material is their lack of rigidity which tends tomake such trays or containers difficult to handle during filling,sealing or normal use, and therefore, it is a principal object of thepresent invention to provide a new and improved form which will overcomeor at least improve the lack of rigidity inherent in such containers.

According to the invention trays or containers of suitablethermo-plastic material are characterised by being of dished form whoseside walls taper outwardly and are radially inwardly bowed from the basetowards the upper portions. The side walls terminate in a rim area whichis first outwardly extended to form a short ledge, then substantiallyupwardly to form a vertical portion and then substantially horizontally,finally being displaced downwards to terminate in a furthersubstantially vertical portion. Alternatively, the downwardly disposedportions terminate in any suitable or desired shape or configuration.

In order that the invention may be fully and clearly comprehended, thesame will now be described with reference to the accompanying drawingswherein there is illustrated in FIGS. l cross-sectional views of traysor containers according to various different embodiments of the presentinvention.

The trays or containers are manufactured from suitable thermo-plasticsheet material such as polystyrene, P.V.C., polythene, polypropylene andanalogous plastics substances. The manufacturing technique employed mayinclude any suitable well known pneumatic or mechanical forming processor combination of the same for producing a tray or container of the typenow to be described.

Referring now to the drawings, it will be observed that the side walls 1of each tray or container of the present invention are radially inwardlybowed as they proceed upwardly from the base or bottom 2 towards theupper portion or extremity of the side walls. The side walls terminateat the upper end thereof in a rim area which is first outwardly extendedrelative to the upper portion of the side walls to form a short ledge 3which is displaced through an angle of at least eighty degrees, andpreferably more than ninety degrees relative to the side walls 1.

The remaining extended portion is further distorted or bent upwardlyapproximately through an angle of 90 to form a substantially verticalpart 4 and thereafter outwardly in a horizontal manner to form a ledge 5whose ultimate extremity is displaced downwardly to form a skirt portionat 6.

The above described construction of the rim area in the container of thepresent invention is clearly illustrated in FIGS. 1-5 of the drawings.Each container shown is provided with portions 3, 4, 5 and 6 which ispeculiar to all examples of the present invention by which trays orcontainers with a parametrical strengthening or stabilizing bead ofinverted channel-shaped cross-section may be provided. This can bereadily depicted in FIGS. 1-2 of the drawings wherein each of thecontainers are provided with portions 3-6, the difference between thesetwo embodiments being that in the FIG. 2 embodiment, the corners of thetray or container are radiused to a greater degree than in the FIG. 1embodiment. In some cases, it may be desirable to extend portion 6 ofthe rim area, and this may be effected in various ways. For example, theextremity of the portion 6 may be flared outwardly and downwardly asshown in FIG. 4 or it may include a horizontally extending shelf portion7 as illustrated in FIG. 3, or may terminate in an upwardly curvedportion 8 such as shown in FIG. 5. Other variations are, of course,possible within the scope of the present invention.

In every instance, the walls of the container are radially inwardlybowed from the area of juncture 9 with the bottom or base 2 to the rimarea of the container. This will not only impart rigidity to the sidewalls of the container to aid, for example, in preventing or at leasthindering side wall bulging due to product overloading, but will alsocooperate with the rim area in imparting increased strength thereto. Inthis latter regard, it is important that the channel-shape rim area ofthe container is provided with a dimensional extent such that the rimarea is capable of deriving both lateral and longitudinal support fromthe radially inwardly bowed side walls 1 so that increased strength isimparted to the rim area as well as the side walls of the container. Thearea of juncture 9 of the side wall with the bottom or base 2 of thecontainer is radially outwardly bowed to also aid in imparting rigidityto the side walls. Additionally, this radially outwardly bowed portion 9has an outer peripheral dimension greater than a predetermined area of aportion of the radially inwardly bowed side walls immediately thereaboveto provide interference between such portions on similarly configuredcontainers when stacked in telescopic relationship, the stackingdepicted by the partial phantom and full line container in FIG. 4. Therelative dimensional relationship between the radially outwardly bowedportion and the radially inwardly bowed side wall portion immediatelythereabove also afiords centralization between adjacent containers asthey are stacked and prevents contact between the radially inwardlybowed portions of adjacent containers. This latter feature isparticularly important in those instances where the exterior side wallsurfaces of the containers are printed since it acts in the manner of ananti-rub feature to protect printed indicia on the side walls of thecontainer.

Either the base or the walls or both base and walls may be shaped orpatterned in any manner desired, such, for instance, as is set forth inour co-pending patent application No. 11,640 of 1963, or the saidportions may have plain or unbroken surfaces.

Although specific embodiments have been shown and described, it is withfull awareness that many modifications thereof are possible. Theinvention, therefore, is not to be limited except by the prior art andby the spirit of the appended claim.

I claim:

A thin-walled one-piece seamless container formed from thermoplasticsheet stock material, comprising peripherally continuous side wall meansof substantially uniform cross-section extending upwardly and outwardlyfrom a bottom wall and terminating in a rim area adjacent the open upperend thereof, said side wall means in the area of juncture with saidbottom wall being first radially outwardly bowed and then radiallyinwardly bowed as it proceeds upwardly therefrom until it terminates insaid rim area, said radially outwardly bowed portion having an outerperipheral dimension greater than a predetermined area of said radiallyinwardly bowed portion immediately thereabove to provide interferencebetween such portions on similarly configured containers when stacked intelescopic relationship, said radially outwardly bowed portion servingas a pilot means in mm tralizing containers as they are stacked andaiding in preventing contact between the radially inwardly bowedportions of adjacent containers, said rim area including a shelfportion. radially outwardly directed from said side wall and beingdisposed therefrom by an included angle of at least eighty degrees, saidrim area further including a substantially vertically extending portionintegrally joined to said shelf portion at its lower end and to asubstantially horizontally extending portion at its upper end, said rimarea terminating in a skirt portion depending from said horizontallyextending portion, at least the major portion of which is generallyparallel to said vertically extending portion whereby to provide aparametrical strengthening bead of inverted generally channel-shapedcross-section,

each portion of said channel-shaped rim area having a dimensional extentsuch that said rim area is capable of deriving both lateral andlongitudinal support from said radially inwardly bowed side wall inimparting increased strength to said rim area.

References Cited by the Examiner UNITED STATES PATENTS 7/ 1877 Hamilton220-74 7/1932 Hart et a1 2292.5 1/ 1934 Shermann 2292.5 3/1955 Cook2292.5 X 11/ 1957 Emery 2292.5 9/ 1958 Dingeldein 22097 X 2/ 1959 Gunn.1/ 1961 Canfield et al 229--3.5 X 2/1964 Fotos 220--97 X 5/ 1964Whiteford 2292.5

FOREIGN PATENTS 8/1959 France.

JOSEPH R. LECLAIR, Primary Examiner.

FRANKLIN T. GARRETT, Examiner.

D. T. MOORHEAD, Assistant Examiner.

